Wednesday, June 16, 2004

Lighting seems simple, doesn't it? You go to the store, get a lightbulb, screw it into a socket, turn it on, and "let there be light". So simple, yet so seductive, and completely innefficient.

With the typical incandescant lightbulb only 10% of the energy put into the lightbulb turns into light. Put another way, incandescant lightbulbs are 90% innefficient. That 90% of the energy turns into heat, which is why these lightbulbs are so hot. The heat is the innefficiency.

The next time you are in a store, take a close look at the different lightbulbs. On the packaging is an important factor in measuring lightbulbs, the "lumens" they output. The lumen is a direct measure of the quantity of light produced by a lightbulb.

There are two major types of lightbulb currently available in the U.S. mass market:

Incandescant: Little changed from Edison's famous invention.

Compact Flourescent: A miniaturized version of the larger flourescent lightbulbs, that are shaped to fit with the usual lightbulb sockets.

As you're in the store comparing lightbulbs, what you should look at is two numbers: The wattage, and the lumens. The efficiency of a lightbulb is directly measured by the wattage required to produce a given number of lumens.

The compact flourescent lightbulbs, as you see by comparring wattage->lumens, is far more efficient than the traditional incandescant lightbulbs. Simply by switching the type of lighting you use, you can get the same amount of light (lumens) while spending less money for the energy.

Even more efficient lighting is coming up, primarily the high intensity LED's. They are far more efficient than even the compact flourescent. At the moment they are unnavailable in a shape suitable for use in regular lightbulb sockets. However they are being used in various ways, such as running lights and turn signals on cars and trucks, traffic signals, flashlights, and more.

Another measure of lighting efficiency is the usable lifetime. While incandescant lightbulbs are rated for 1000 hours of use, compact flourescent are rated for much more, around 10,000 hours, and LED lighting is rated for even more, 100,000 hours or more.